Control device



g- 1942- E. J. DILLMAN CONTROL DEVICE Filed May 22, 1939 3 Sheets-Sheet1 new INVENTOR BQAMY ff. $4M W /C. M

at, ATTORNEY 3 Sheets-Sheet 2 INVENTOR W BY W .4 ATTORNEY FIG-5 PatentedAug. 4, 1942 Earnest J. Dillman, Detroit, Mich, assignor to DetroitLubricator Company, Detroit, Mich, a corporation of Michigan ApplicationMay 22, 1939, Serial No. 274,894

32 Claims. (01. 200-83) My invention relates generally to new and usefulimprovements in control devices and more particularly to those operatingin accordance with pressure or temperature.

An object of my invention is to provide an apparatus operable to controla means in response to pressure or temperature.

determinedabnormal change in pressure beyond one of the predeterminedlimits to indicate the abnormal condition.

Another object of my invention is to provide an apparatus forcontrolling the operation of a refrigerating system to maintain thecooling coil pressure between predetermined pressure limits. 1 I

Another object of my invention is to provide a refrigeration controlwhich is easily adjusted to maintain various temperatures in therefrigerated compartment, and maintain a-predetermined constant cut-inpoint to insure complete defrosting of the cooling coil each-cycle ofoperation;

Another object of my invention is to provide an apparatus which normallyacts to operate a refrigerating system according to a condition of thecooling coil but which is also operable to maintainthe high sidepressure between predetermined limits.

Another object of my invention is to provide an apparatus by whicheither of the predetermined high side limits may be adjustedwithout-change of the other limit.

' Another object of my invention is to provide a new and novel pressureor temperature operated switch simple in operation, installation andmanufacture.

Another object of my invention is to provide a new and novel apparatusin which the various cooperating elements may be easily removed as unitsfor repair or replacement.

The invention consists in the mp C011- struction and combination ofparts, to be more fully described hereinafter and the novelty of whichwill be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of thisspecification, I have fully-and clearly illustrated a preferredembodiment of my invention, in which drawings Figure 1 is a view infront elevation of my control apparatus with the cover and coverattaching post removed;

Fig. 2 is a side view of certain pressure operating mechanism takensubstantially along the line 22 of Fig. 1, but with its front casingwall broken back to show more clearly the indicating means, and with thelocking members removed;

Fig. 3 is a top plan view of the apparatus shownin Fig. 1 but with thepressure fitting in section and thecover and its post in place;

Fig. 4 is a view along the line 44 of Fig. 3 and taken in the directionof the arrows;

Fig. 5 is a view along the line 55 of Fig. 4 and taken in the directionof the arrows;

Fig. 6 is an enlarged detailed view of a portion of the switchmechanism, showing the cooperative relation of the plunger member andthe snap springs;

Fig. 7 is a view in side or end elevation of the switch mechanism casingshowing certain overload cut-out means; 7

Fig. 8 is a view taken along the line 8 of Fig. 7 in the direction ofthe arrows;

Fig. 9 is a view substantially along the line $9 of Fig. l'showing aportion of the switch structure;

Fig. 10 is a view in end elevation of a portion of the apparatus shownin Fig. -1 and showing the arrangement of levers and springs;

Fig. 11 is a View with the top main casing wall removed and showing aportion of the apparatus shown in Fig. 10;

Fi 12 is a view in front elevation of a modifled form of lever andspring arrangement;

Fig. 13 is a view in end elevation of the modification of the apparatusof Fig. 12;

Fig. 14 is a top plan view of an external manual adjusting means shownin Fig. 12, and

Fig. 15 is a plan view of the resetting lever showing its cooperationwith the plungermember.

Referring to the drawings by characters of reference the numeral ldesignates generally my control apparatus having a substantially U-shaped sheet metal member 2 having a vertical connecting or rear wall 3and parallel, horizontally extending, upper and lower walls 4, 5,respectively. A U-shaped member 5 cooperates with the member 2 to forman enclosed casing, and is held in place by means of a thumb screw 5threaded into a cover attaching post 5, preferably an angle memberhaving its front flange secured at its top and bottom ends to the walls4, 5. A low pressure power element 6 is secured to the outside of thewall 5 and a high pressure power element 1 is secured to the outside ofthe wall 4. A switch mechanism or unit 8 is secured within the casing tothe vertical wall 3, as by a screw 8 Secured to the inside of the wall 5is a fulcrum or bracket member 9 having upturned ears III, II and ahorizontally disposed base portion I2 reenforced by having upwardly bentedge portions I3. The ears II], II have aligned apertures which receivea shaft or rod member I4 extending parallel to the wall 5 and normal tothe wall 3, and on which are journaled lever members I5, I6. The levermembers I5, I6 are plate-like with upturned reenforcing side portions I5IIS in which are aligned apertures for receiving the shaft I4. The levermember I6 overlies the lever member I5 and the members extendsubstantially parallel to wall 5 and overlie the power element 6.

The power element 6 comprises a cup-shaped casing member having at itsopen end an outturned flange 2| having apertures through which thescrews extend to secure the cup-shaped member rigidly to the wall 5.Within the casing 20 and located adjacent its open upper end is an annular member 22 having a flange portion 23 sealed in fluid-tightrelation to the casing 20. A bellows 24 has one end rigidly secured tothe annular member 22 and extends therefrom toward the bottom end wall25 of the casing member 20, where it is sealed, as at 26, to the flangeportion of a cup-shaped member 21. The member 21 extends within thebellows 24 and has an aperture through its bottom wall 28 in which issealed a thrust member 29 having one end portion 29- extending towardthe end wall 25 and the other end portion 29 extending through anaperture 30 in the wall 5 and terminating adjacent the lever member I5.A nut-like member 32 is secured in fluid-tight relation in an aperture3| through the wall 25 and cooperates with the end portion 29 of thethrust rod 29 to limit expansive movement of the bellows 24. Thenut-like member 32, casing 20, annular member 22, bellows 24, cup-shapedmember 21 and thrust member 29 cooperate to form a sealed, pressureresponsive, expansible-contractible chamber 32*. A conduit 32communicating with a source of pressure, which may be the suction lineof a refrigerating system, is secured by means of a nut 32 to the member32, and the fluid pressure is transmitted to the chamber 32 through apassageway 32 ccmmunicatively connecting the conduit 32 with the chamber32*. The passageway 32 has a restricted throat portion 32 which acts toprevent any rapid fluctuation of pressure, which might occur in theconduit 32 from being readily communicated to the chamber 32*.

Concentric with the thrust member 29 and interposed between thecup-shaped member 21 and the nut-like member 32 is a helical coil spring33 which tends to collapse the bellows 24 and acts to supplement theforce of the fluid pressure within chamber 32 The lever members I5, I6have apertures 40, 4| respectively, concentric with the thrust member29. A hollow, cone-shaped force transmitting member or abutment 42 ismechanically secured to the lever member I5 within the aperture 49 andextends upward through the aperture 4| in the lever member I5 but isspaced from the member I6 so that the lever member I5 is free to movewithout movement of the member I6. Screw-threaded in the end portion 29of the thrust member 29 is a coneshaped abutment member 43 having itspointed portion or apex received within an internal apex portion of thehollow, cone-shaped member 42.

A screw-threaded, bolt-like member 50 is fixed against rotation andsecured within an aperture in the wall 4 of the casing 2, as by peening,and extends downward toward the wall 5 concentric with the thrust rod29. A second bolt-like member 5| is secured against rotation in likemanner to the wall 4 and extends downward toward the lever member I6intermediate the aperture 4| and the end portion of the lever farthestaway from the fulcrum member 9. Screw-threaded on the bolt-like members59, 5| are threaded adjustment nuts or abutment members 52, 53respectively. A helical coil spring 54 is held under compression betweenthe abutment member 52 and a spring abutment member 55 having a recessedportion with an internal, coneshaped base which receives the apex of theconeshaped member 42 so that the force of the spring 54 may betransmitted through the cone-shaped member 42 to the thrust member 29 ofpower element 6 to oppose upward or counter-clockwise movement of levermember I5 and the collapsing movement of bellows 24 due to the spring 33and the fluid pressure within chamber 32*. A thrust member or springsupporting post 56 is secured to the lever member I6 concentric with thebolt-like member 5|, and extends upward from the lever member I6 towardthe bolt-like member 5|, terminating in a needle-like point 51 which isreceived within an indented portion of a spring abutment member 58.Interposed between the abutment member 58 and the adjustment member 53is a helical coil compression spring 59 which urges the lever member I6in a clockwise direction. The spring 54 is the range adjusting springand the spring 59 is the differential adjusting spring. The peripheralsurfaces of the adjustment nuts 52, 53 are knurled and cooperate withthe outturned end portions of a U-shaped spring or unitary lockingmember 69 secured to the vertical connecting wall 3 as by means ofscrews. The member 60 has its arms or sides terminating in verticallyextending, outturned edges 60 which frictionally engage the knurledportion of the adjustment nuts 52, 53 so that they may be readilyrotated by hand, but are held to prevent unwanted rotation duringoperation of the instrument. The lever member I5 is limited in itsclockwise rotation by an upward facing shoulder 62 of a stop member 63secured to the wall 5. Clockwise movement of lever member I6 is limitedby means of an upward facing shoulder 64 on the member 63 and spacedfrom the shoulder 62 and so arranged that the lever members I5, I6, whenagainst their respective stop shoulders, are held in spaced relation.Counterclockwise movement of the lever members I5, I6 is limited byengagement of lever member I6 with a downward facing shoulder 65 on thestop member 63.

The switch mechanism 8 comprises a hollow, open sided casing or housingmember 10 preferably made of molded, electric insulating material, suchas Bakelite, having its vertical open side facing away from the levermembers I5, I6

and closed by ahollow cover member H which may be made of pliablematerial, such as rubber, having the marginal edge of its side wall heldto and overlapping the marginal edge of the side wall of the casing in astressed condition. A projection H on the rear face of the casing 10 isreceived and fits within an aperture through the wall 3 of the member 2to facilitate the locating of the mechanism 8 during the assembly of theapparatus l, or in the event of replacement, and to cooperatewith thescrew 3 to hold the casing 10 in position. Secured to the wall 12 of thecasing Til and within a chamber 13 formed by the wall 12 and covermember H is a pair of switch mean 14, 15 operated by a common plungermember 16 of electric insulating material extending parallel to the wall3 which reciprocates in and is carried within an aperture 11 through thewall-12. The plunger member 16 is rectangular in cross-section to fitthe rectangular aperture 11 so that the plunger member is held againstrotation. Surrounding the wall aperture 11 and integral with the wall 12is a portion 18 extending outwardly and which has an annular, outwardfacing shoulder providing a cylindrical cap member receiving portion 19.The portion 18 also provides an elongated bearing surface for theplunger member 15 so that there will be less danger of cocking andconsequent sticking of the member 16 in its reciprocation. The plungermember 16 has at its inner end, within the casing 70, a vertically andlongitudinally extending blade portion 89 having two upward opening,longitudinally spaced, pearshaped apertures 8 I, 82 which receive.respectively, transversely extending snap springs 83, 84 which are thin,highly flexible and resilient blades. The horizontally extending snapsprings 83, 84 have their end portions held in opposed, V-shapedvertical grooves in the spaced, downward extending arms of inverted,U-shaped members 85, 86 respectively, which hold the springs in a bowedor stressed position. The restricted portion of the aperture BI isnarrower than the restricted portion of the aperture 82, and preferablysubstantially fits the spring 83. Movement of the plunger member 16inwardly into the casing 19 will cause the springs 83, 84 to flex with asnap action and bow toward the cover member TI. The narrow restrictedportion of the aperture 8| will engage and fiex the spring 83 to itsoutwardly bow-ed position, away from the wall 12, and upon continuedmovement of the plunger member Hi the restricted portion of aperture 82will engage and flex the spring 84 to its outwardly bowed position. Uponreverse movement of the plunger member 16 the spring 84 will be engagedand flexed to inwardly bowed position, bowing toward the wall 12. Undernormal movement of the member 15 the width of the restricted portion ofaperture 82 is sufficient so that the spring 84 remains bowed toward thewall 12. Movement of the plunger member 76 toward the right aftersprings 83, 84 are bowed toward wall 12 is limited by a shoulder 81 onthe blade portion 80 which engages the wall 12 thereby limiting thisbowing of the springs.

A post member 99 is molded into and projects from the casing wall l2 andhas secured thereto in horizontally spaced relation, a pair ofvertically extending, overlying switch blade members 9|, 92 which extendupward from post member 99. Adjacent their upper ends, the blade members9|, 92 are twisted through 90 and each has in its upper end, an end slotthrough which the snap springs 83, 84 respectively extend and fit. Theblade members 9|, 92 carry contact members 93, 94 which cooperaterespectively with stationary contact members 95, 96 carried by posts 91,98 molded in and projecting from the casing wall 12. The blade members9|, 92 are stressed toward the fixed contact members 95, 96 respectivelyso that they act with the springs 83, 84 to move the contact membersinto and to hold the contact members in engagement. Movement of theplunger member 16 into the casin 10 causes the snap spring 83 to snap sothat it is bow-ed outward or toward the cover member II causing thecontact member 93 to move into switch closed position with the contactmember 95. Continued movement of the plunger member 16 toward the coverH causes snap spring 84 to snap so that it is bowed outward or towardthe cover member ll thereby causing contact member 94 to move intocooperative relation with the contact member 95. The U-shaped member 85,86 are held rigidly to the casing wall 12 and within the chamber 13 byscrews 99, I00 and are held in spaced relation relative to each other bytubular members IUI, M2 on the screws 99, I99 respectively. A plate-likemember I03 is held at its ends to the U-shaped member 86 by the heads ofthe screws 99, I90 and has a downward, ofls-et portion H14 acting as astop to limit bowing movement of the snap spring 84 under inwardmovement of the plunger member 16 so that the springs 83, 84 will not bedislodged from the U-shaped members 85, 86. Downwardly open aperturesI05, H16 in the underside of member Hi3, intermediate the offset portionI04 and the portions of the member 193 adjacent the heads of the screws99, I09, serve to receive and permit free movement of the blade portionand the apertured or upper end of the switch blade member 92. A rubbercap or sealing member I01 has one portion fitting tightly around andheld stressed to the plunger member 16 and another portion fittingtightly around the casing portion T8 and held stressed to the shoulder19 so that it serves to seal the aperture IT to prevent fiow of fluidwith moisture or dust into the chamber 73. The member ID! hasintermediate its ends an outturned, circumferential bellowslike foldwhich permits easy reciprocation of the plunger member 16 without anysubstantial stress on the cap member.

An overload device, generally designated Ill], is carried on and securedto the outer surface of the wall 12. The overload device Iii] is of thewell known, solder pot type of construction, having a ratchet wheel Illcarried on an axle H2 which is received within a tubular member 3.

A low temperature melting solder normally prevents rotation of the axleH2 in the tubular member H3. The tubular member H3 is rigidly held by aplate-like member H4 which has a portion H5 secured to the wall 12. Ajointed or articulated, pivoted lever member I56 has a substantiallyhorizontally extending portion Hfi pivoted, as at ll'l, to an upturnedhorizontal ear H8 of the portion H5. An L-shaped portion H9 is pivotedto the vertical portion H9 as at I20, and has a tooth l2! which engagesin the ratchet wheel II I to prevent the lever H6 from being movedoutward from wall 12, due to the force of a helical coil compressionspring E22, under compression intermediate the portion H5 and thevertical part of the L-shaped portion H9. The spring I22 is positionedby lugs I23, I24 secured respectively to the portions H9, H5. A heatercoil I25, electrically insulated from the tubular member H3, is adaptedto be in series circuit with the contact members 93, 95. The heater coilI25 is so proportioned relative to the normal load to be controlled bythe contact members 93, 95 that it does not generate suflicient heat tomelt the solder which holds the axle I I2 rigid with the conduit memberII3, but upon a predetermined increased load th heater coil will giveoff suflicient heat to melt the solder and release the ratchet wheel.Release of the ratchet wheel I I I allows a plate-like member I26secured to the L-shaped portion II9 to engage a bracket arm I2I securedto the plunger member I6. On the end of lever portion II9 there is ahorizontal toe II9 which rests on the wheel upon disengagement of toothI2I so that the tooth may be readily reengaged. The spring I22 hould beof sufficient strength so that upon engagement of the plate member I26and the bracket arm I2I it will act to move the plunger member I6outward to open the circuit through contact members 63, 95 irrespectiveof any closing force exerted on the plunger member I6. This will alsocause the circuit controlled by the contact members 94, 96 to be opened.

The contact members 93, 94 are electrically connected by means of theblades 9|, 92 respectively to the supporting post 99, and therethroughto a bus bar or conductor strip I28 having a binding post connection I29for receiving a connecting wire from a source of electrical energysupply. The contact member 95 is connected by means of post 91 to a busbar or conductor strip I30 which has a binding post I3I for receivingone end of the heater coil I25. The other end of the coil I25 isattached to a binding post member I32 secured to the casing I and whichis adapted to receive a wire leading to the apparatus to be controlledby the switch means I4. The contact member 96 is connected through post98 and a bus bar or conductor strip I33 to a binding screw which isadapted to receive a wire leading to the alarm circuit controlled by theswitch means I5.

A resetting mechanism (Figs. 1, 3 and 15) is carried by the top wall 4for manually reengaging the tooth I2I and the ratchet wheel II Isubsequent to cooling of the solder holding the axle II2 to the tubularmember II3. The resetting mechanism comprises a lever member I34pivoted, as at I34 to the wall 4 and having an upturned portion I35extending through an arc-shaped aperture I36 in the casing wall 4 formanual operation external of the casing. The lever member I34 has adownwardly projecting ear portion I31 which is adapted upon pivotalmovement of the lever member I34 to engage the plate member I26 to movethe articulated lever member H6 in a counterclockwise direction so thatthe tooth I2I again engages the ratchet wheel III. The lever member I34also has a cam edge portion I3I" which engages a post member I38 carriedby the plunger member I6 so that upon resetting movement of the levermember I34 the switch means I4, I are maintained in open circuitposition regardless of the fluid pressure in chamber 32 With thisconstruction it is impossible to hold the resetting mechanism lever I34in resetting position and maintain either of the switch means I4, I5 incircuit closed position so that the overload is thereby renderedineffective to protect the overloaded circuit.

The lever member I5 is connected to the plunger member 16 through avertical projecting or upstanding arm I having a portion or flange I5Iextending substantially normal to the plane of the vertical wall 3.Secured to the lower end part I52 of the portion I5I, in a manner suchas by riveting, is one end of a flexible blade I53 which extends upwardfrom the part I52 and inclines toward the flange I5I by reason of theinclination of the part I52. The upper end portion of the blade I53 hasits side edge received within a converging-diverging slot or apertureI54 in the plunger member I6 so that pivotal movement of the levermember I5 will move the plunger member causing the switch blades 9|, 92to make or break their respective circuits. The blade I53 is preferablyrelatively stiff and so proportioned relative to the resistance of thesnap springs 83, 84 that movement of the plunger member I6 by the levermember I5 will cause no bending or springing of the blade I53.Screw-threaded into the upper end of the portion I5I and extendingthrough an aperture in the blade I53 is an adjustment member or screwI55 having a flange against which the blade I53 bears and is held by itsinherent resilience. The member I55 moves or flexes the blade I53relative to the portion I5I so that the position of the lever member I5relative to the position of the plunger member I6 at which the contacts93, 95 and 94, 96 are closed or opened, may be adjusted. The blade I53,due to its ability to be flexed. allows movement of the plunger memberI6 relative to the lever member I5 for movement of the plunger member toopen circuit position when the power element 6 calls for closed circuitposition of the switch means I4, I5, and for other purposes to behereinafter described.

Fluid pressure is introduced to the power element 6 by means of theconduit 32 and increase I in fluid pressure within the chamber 32 causesthe thrust member 29 to move inward toward the wall 4 and rotate thelever member I5 in a counterclockwise direction. Upon predeterminedmovement of the lever I5 it engages a downwardly projecting lug I63 ofthe lever member I6 so that continued rotation of the lever member I5will cause corresponding rotation of the lever member I5. It may be seenthat the helical coil spring 54 opposes initial movement of the thrustmember 29, but after predetermined movement of the lever I5 to causeengagement with the lug I63 of the lever member I6, further movement ofthe thrust member 29 is opposed by the sum of the forces of the springs54, 59. The relative position of the plunger member I6 and lever memberI5 is so adjusted by the adjustment member I55 that the contact member93, are not moved into closed circuit position until lever member I5 hasengaged and picked up lever member I6, while in the reverse movement thecontact members 93, 95 are not moved to open circuit position until thelever member I5 has left the lever member I6. It can easily be seen thatthe force exerted by the spring 59 will determine the difierential inpressure between that necessary to move the contact members 93, 95 toclosed circuit; position and that necessary to move the contact members93, 95 to open circuit position.

As was set forth hereinbefore, under normal conditions of operation thesnap spring 84 will not be flexed upon movement of the plunger member 16because of the relatively greater width of the restricted portion of theaperture 82 with respect to that of the aperture 8|. However, should thefluid pressure within chamber 32 increase substantially beyond thatnecessary to rotate the lever members I5, I to cause snap spring 83 tovbow outwardly toward the cover member II, or into switch closedposition, then the snap spring 84 will be engaged by the wall ofaperture 82 and flexed into a bowed position similar to that of spring83, closing the contact members 94, 96 and thereby energizing the alarmto attract, attention to the abnormal condition.

The highv pressure power element I comprises a hollow casing member 209which preferably has an upper end wall 29I and a flanged, open lower end292 secured to the outside of the wall 4 by means of screws. Locatedwithin the casing 200 is a pair of plate-like lever members 293, 294having downwardly projecting fingers 203 254 respectively extendingthrough the open end of the casing 290 and through an aperture 205 inthe wall 4 into the casing 2 so that one finger is located on eithersideof theblade E53 adjacent the plunger member I5. The lever members293, 294 are pivoted on pins 295, 2W respectively which have theiropposite ends secured in apertures in the walls of the casing 256.Carried within an aperture 20am the end wall 29I and overlying the levermember 203 is a pressure responsive element, generally designated 269.The element 289 comprises a tubular member ZIEI having an end wall 2IIin which is a restricted orifice 2I2. The lower end of the tubularmember 2I9 receives, in fluid-tight relation, the upturned flange 2|3 ofan annular member 2I5. A bellows 2H5 has one end sealed to the annularmembers H5 and has its other end extending upward into the tubularmember H9. The upwardly extending end of the bellows 2I5 is sealed to aplate-like member 2 IT. The wall 2I I, members 2H), 2I5 and 2H, andbellows 2I6 cooperate to form a sealed, eXpansible-contractible,pressure responsive chamber 2II communicating through the orifice 2I2with a conduit member 2I'I which may be connected to a refrigeratingsystem high side, suchas at the outlet of the compressor, so that highside refrigerant pressure is communicated to the chamber 2II Securedwithin a central aperture of the platelike member 2I'I is one end of athrust member 2| 8 which has its other end extending downwardthrough thebellows 2I6-to engage a second thrust member 2I9 having engagement withthe lever member 294. .The thrust member 219 is slidably received andcarried within a tubular member 229 rigidly secured to the lever member293. The tubularmember 229 has at its lower end a wall 22I which has anaperture substantially fitting the thrust member 2I9 and guiding it inits reciprocal movement. The thrust member H9 is urged against an uppershoulder 222 of the tubular member 220 by a helical coil spring 223interposed between the wall 22I and a shoulder 223 of the member 2I9.The lever members 253, 294 are limited in their counterclockwise andclockwise rotational movement respectively by a stop member 224 whichmay be a pin or shaft extending through aligned apertures in the casing200.

The lever member 294 is urged in a clockwise direction against the stopmember 224 and the thrust member 219 by a helical coil spring 239heldunder tension by means of an adjustment screw'23l extending throughan aperture in the top wall 2OI and received by a screw-threaded nut 233to which the spring 239 is securely fastened. The other end of thespring 230 is canchored to an upturned flange on the lever 204. Thelever member 203 is urged in a clockwise direction away from the stopmember 224 by a helical coil spring 234, thetension of which iscontrolled by means of an adjustment screw 235 extending through anaperture in the top casing wall 25! and a nut 236 secured in the upperend of the spring 232 so that thethrust members 2 I8, 2I9 arecontinually in engagement. The other or lower end of the spring 234 isanchored to a forward extending flange on the lever 203. The spring 223must exert a greater force than the maximum force exerted by the spring234 so that rotation of the lever member 253 is directly responsive toand in accordance with the position of thrust member 2I8 prior toengagement of lever member 293 and stop member 224. Upon a predeterminedlow pressure in the chamber 2 Il the spring 234 will rotate the levermember 293 so that the finger 253 will engage and flex the blade I53relative to lever member I5 to move the plunger member "I6 to close thecontactmembers 93, of switch means I5. Upon a predetermined increase inpressure in the chamber 2H to the low limit of normal operatingpressure, the thrust member 258 will rotate thelever member 253 againstthe stop member 224, with the finger 203 out of opposing engagement withthe blade I53, so that the plunger member I6 is again operable by and inaccordance with the fluid pressure in chamber 32* Upon a predeterminedmaximum high pressure in chamber 2H the thrust member 2I8 is urgeddownward, moving the thrust member 2I9 downward within the tubularmember 229 of the lever member 293 which is held against rotationbyengagement with the stop member 224. The downward movement of the thrustmembers 2 i8, 2 I 9 acts to rotate lever member 294 in acounterclockwise direction so that the finger 204 engages blade I53 tomaintain the plunger member 16 in a position to hold the switch means14, 15 in open circuit position irrespective of the pressure in chamber32 If the switch means 14 is in closed circuit position, due to thepressure in chamber 32 when the maximum high pressure occurs in chamber2H then the finger 294 will engage and move the blade I53 toward theright, carrying with it the plunger member I6 and opening the switchmeans 14. Upon a predetermined decrease in fluid pressure within thechamber 2I'i the spring 238 will rotate the lever member 294 so that thefinger 294 is spaced from the blade I53 and the switch means I4, I5 areagain operable by and in response to fluid pressure within chamber 32 Itwill thus be seen that the spring 223 acts to maintain the thrust member2I9 rigid with the lever member 293 during low pressure operation of thepower element 299 and allows relativemovement during high pressureoperation of the power element 299.

The nuts 233 and 233 carry indicator pointers 238, 231 respectively,which cooperate with suitable indicia plates 2.39, 2 59 to indicate thepressures at which the lever members, 293, 254 are rotated to engage theblade I53 and move it to operate the switch means I4. The adjustmentscrews 23I, 235 have longitudinal slots. 242 in their heads which arelocated external .of the wall 2BI for reception of a suitable tool, suchas a'screw driver, so that the tension of springs 23!), 234 may beeasily adjusted. After adjustment, the heads of the screws 23I, 235 areconcealed by caps or looking members 243, 244, held in position byscrews 2'45, 246, to prevent careless tampering with the adjustmentscrews 23I, 235.

In Figs. 12, 13 and 14 I have shown a somewhat modified form of myinvention. The helical coil compression spring 59 has been replaced by atension spring 360 having one end 33I secured to a combination thrustand stop member 302 rigidly secured to the lever member I6. The member302 has a flange or head portion 363 extending below and spaced from thelever member I6 and engageable by the lever member I5 upon clockwisemovement thereof. The upper end 304 of the helical coil tension spring300 is rigidly secured to a nut-like member 305 threaded to a bolt-likeadjusting screw 306. The adjusting screw 306 extends upward through anaperture in the wall 4 and has a flange or collar portion 301 abuttingthe top surface of the wall 4 and acting to prevent downward movement ofthe adjusting screw 306 due to the force of the spring 300. The screw306 carries, intermediate the wall 4 and the member 305, a knurlednut-like member 30! held rigid with the screw 306 by a set screw. Theserrated or knurled edge of member 391 cooperates with the springlocking member 60 to prevent unwanted movement of screw 306, similarlyto the cooperation of the member 60 and nut 53. A knurled handle member308 is suitably secured to the adjusting screw 306 above the collar 301by a set screw 30!! so that the adjusting screw 396 may be easilyrotated manually externally of the casing. The handle member 398preferably carries a pointer member 3|0 which cooperates with a suitableindicia plate 3II rigid with the casing wall 4 to indicate the settingof the adjustment screw 306. The member 3|0 also cooperates with a stopor post 3II to limit rotation of the screw 306 to less than 360. Areenforcing post member 3| I has one end secured to the wall 4 and itsother end secured to the wall 5, and prevents relative movementtherebetween. An indicia plate 3| I may be secured to the post member 3|I in a suitable manner, such as by screws, and cooperates with an indexfinger movable by the adjusting nut 52 to indicate the setting of thespring 54. Rotational movement of the lever member I6 in acounterclockwise direction, due to the force of the spring 330, islimited by engagement of the lever member IS with a flange portion 3I2of a stop member 3I3 secured to the wall 5. The stop member 3I3 has asecond flange 3I4 which cooperates with lever member I to limit movementthereof in a clockwise direction under influence of the coil spring 54.In this form of apparatus,

the blade I53 is adjusted so that the plunger member I6 does not movethe snap spring 83 through center to close switch means I4 until theforce of differential spring 300 is absorbed by the stop member flangeportion 3|2 so that the pressure in the power element 6 to close theswitch means I4 is determined solely by the range spring 54. Theposition of blade I53 is such that on the return movement of plungermember I6 to open the switch means I4, by decreasing pressure in element6, the snap spring 83 is not moved through center until the opposingforce exerted by the differential spring 300 is picked up by the levermember I5 by its engagement with the head portion 303 of lever memberI6.

It may be seen that in the apparatus shown in Fig. 1, engagement andsynchronous movement of the lever members I5, I6 occurs upon increase influid pressure within the chamber 32 In the modification as shown inFigs. 12, 13 and 14, the engagement of and synchronous movement of thelever members I5, I6 occurs upon reduction of the fluid pressure inchamber 32*. In this manner I have provided, in the construction ofFigs. 12, 13 and 14, a means for varying the differential in pressurebetween that necessary to move the switch means I4 to closed circuitposition and that necessary to open the switch means I4 without changingthe adjustment or force required for moving the switch means I4 intoclosed circuit position. The apparatus as shown in Fig. 1 maintains aconstant switch opening pressure irrespective of change in the forceexerted by the differential spring 59 for varying switch closingpressures of the switch means I4. In the apparatus shown in Fig. 1, andthe modification shown in Fig. 12, adjustment of the force exerted bythe range spring 54 changes both the cut-in and cut-out pressuresrequisite in the chamber 32 to cause the switch means I4 to move to openand closed positions without however changing the pressure differential.

My apparatus is particularly adapted for use on a refrigerating systemin which the pressure within the chamber 32 is either sensitive directlyto the fluid pressure within the evaporator of the system, or thetemperature of the evaporator as reflected in a sealed system containingan amount of temperature sensitive, volatile fluid and connected to thepower element 6. The chamber 2 Ha is adapted to be responsive directlyto the fluid pressure in the condenser side of the refrigerating system,or to be responsive to the temperature thereof as reflected by thepressure in a sealed system containing an amount of temperaturesensitive, volatile fluid and connected to the power element I. Undernormal operation of the refrigerating system the adjustment of thesprings 230, 234 is such that the lever members 203, 204 are heldagainst the stop member 224 and the operation of the switch means I4, I5is directly controlled by the pressure within chamber 32*. Upon apredetermined high pressure in the chamber 32 the thrust member 29 willhave rotated the lever members I5, I6 to move the plunger member I6 tothe left, facing Fig. 4, so that the contact members 03, 95, whichcontrol the circuit to the compressor motor, will be in closed circuitposition. Should the fluid pressure within chamber 32 increasesubstantially above the predetermined high pressure, the plunger memberI6 will have been moved still further to the left, facing Fig. 4, sothat the contact members 94, 96 will be in closed circuit position andenergize an alarm circuit to call the operators attention to theincreased temperature of the refrigerating system evaporator. Normallyhowever the pressure and temperature of the evaporator does not exceedthe predetermined high pressure at which the contacts 93, move to closedcircuit position. Upon a predetermined low pressure in the chamber 32which reflects a corresponding low temperature and pressure in theevaporator, the lever members I5, I 6 will be rotated by theirrespective springs 54, 59 so that the plunger member I6 will have openedthe contact members 03, 95 to stop operation of the refrigeratingcompressor. Should it be desired to increase the differential ofpressure and temperature maintained in the refrigerating evaporator, itis only necessary to adjust the adjusting nut 53 so that the force ofthe spring 59, acting to rotate the lever member 19 in a clockwisedirection, is increased. However, it will be noted that this increaseindifferential is accomplished by adjusting the pressure at which thecontact members 93, 95 are moved to closed circuit position. As was setforth hereinbefore, the contact members 93, 95 are moved to closedcircuit position subsequent to engagement of the lever members l5, l6 sothat rotation thereof is opposed by the sum of the forces of springs 54,59, while the contact members 93, 95 are moved to open circuit positionsolely under the influence of the spring 54.

The modification shown in Figs. 12, 13 and 14 cooperates insubstantially the same manner in controlling the refrigerating systemexcept that instead of the differential adjusting spring 399 controllingthe point at which the contact members 93, 95 are moved to closedcircuit position, it adjusts the point at which the contact members aremoved to open circuit position, or the low temperature limit of theevaporator. It will be seen that upon a predetermined high pressure inthe chamber 32 the lever member l will have been rotated by the thrustmember 29 away from the head portion 303 so that the spring 54 is thesole spring acting in opposition to the thrust of the thrust member 29.Upon a predetermined lower fluid pressure in the chamber 32 the levermember I5 will have rotated sufll ciently in a clockwise direction underthe influence of spring 54 so that the lever member is in engagementwith the head portion 393 and springs 399 and 54 cooperate together todetermine the opposing force exerted upon the thrust rod 29. Themodification shown in Figs. 12, 13 and 14 is particularly adapted torefrigerating systems, such as meat storage refrigerators, in which itis desired to insure positive defrosting of the refrigerating coils orevaporators each cycle of operation, and yet having a simple and easymeans for adjusting the average temperature maintained in therefrigerator.

The power element 299 does not act with a snap but acts with amodulating action to move the plunger member 16 to open or closedposition. At pressures approaching the predetermined low pressure orpredetermined high pressure of the power element 299, the blade I53 hassufficient rigidity to enable the power element 6 to move the finger 293or finger 294 against the force of the power element 299. In the eventthat the pressure within power element 299 decreases to a pressure whichis somewhat greater than the predetermined pressure at which the finger293 acts to urge the plunger member 16 to closed circuit position, butless than the pressure necessary to maintain the lever member 293against the stop 224, the finger 293 will be urged into a positionslightly to the left, facing Fig. l, of that shown. In such a positionthe finger 293 acting through the power element 299 will be moved by andopposed movement of the blade [53 during clockwise movement of the bladeE53 and the power element 299 will thereby act to reduce the pressure ofelement 6 neces sary to open the switch means 14 and/or 15, but such aposition of the finger 293 and power elment 299 will not affect thepressure of element 9 necessary to close the switch means 14 and/or l5.In the event that the element 299 is acting to urge the finger 293 intothis said position, the power element 299 will act to increase thepressure differential of the element 6 so that the refrigerating system,which may be controlled by the apparatus shown and described, will bemade to operate with a lower average cooling unit temperature. Suchoperation may be beneficial and desirable under certain operatingconditions. In a similar manner, the finger 294 will act to increase theoperating pressure differential of the element 6 at fiuid pressures ofthe element 299 slightly lower than the predetermined pressure at whichthe power element 299 acts to open the switch means l4, l5 irrespectiveof fluid pressure within the power element 6. In this event however itis the pressure of the power element 9 necessary to move the switchmeans 14 and/or 15 to closed circuit position which is varied, ratherthan that necessary to move the switch means to open circuit position.

It will now be seen that I have invented an apparatus which is operableto control a plurality of electrical circuits in response to a fluidpressure, and the electrical circuits are also 0D- erable to becontrolled by a second normally inactive power clement upon occurrenceof predetermined, abnormal conditions. It may also be seen that I haveinvented a simple and easily installed and serviced apparatus in whichthe various parts thereof are easily removed for repair or replacementof parts, without unnecessary alteration to the unaffected parts of theapparatus.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. A control device comprising switch means, an overcenter member foractuating said switch means, a plunger operable to move said memberovercenter, a lever, an arm on said lever and operable to move saidplunger, a power element operable to move said lever thereby to causesaid arm to move said plunger, means opposing movement of said lever bysaid element, a second lever concentrically fulcrumed with and movableby said first-named lever, means opposing movement of said second leverby said first-named lever, said arm being movable relative to said firstnamed lever, and means to move said arm to operate said plungerirrespective of the movement of said levers.

2. A control device comprising switch means, an overcenter member foractuating said switch means, a plunger operable to move said memberovercenter, a lever, an arm on said lever andoperable to move saidplunger, a power element operable to move said lever, means opposingmovement of said lever by said element, a second lever concentricallyfulcrumed with and movable by said first-narned lever, means opposingmovement of said second lever by said firstnamed lever, said arm beingmovable relative to said first-named lever, a lever engageable with saidarm, and automatic means operable through said last-named lever to movesaid arm to 0perate said plunger.

3. A control device comprising switch means, an overcenter member foractuating said switch means, a plunger operable to move said memberovercenter, a supporting shaft, a lever journaled on said shaft andoperable to move said plunger, a force transmitting member carried bysaid lever, a power element engaging said force member and operable tomove said lever, means engageable with said force member and operable tooppose movement of said lever by said element, a second leverconcentrically fulcrumed with and movable by said first-named lever andjournaled on said shaft, said second lever being positioned intermediatesaid first-named lever and said engageable means and having an aperturethrough which said force member extends, and means opposing movement ofsaid second level by said first-named lever.

4. A control device comprising switch means, an overcenter member foractuating said switch means, a plunger operable to move said memberovercenter, a lever having a flange, a flexible blade fixed to saidflange and operable to move said plunger, means to adjust said bladerelative to said flange, a power element operable to move said lever,means opposing movement of said lever by said element, a second leverconcentrically fulcrumed with said first-named lever and movable by saidfirst-named lever, and means opposing movement of said second lever bysaid first-named lever.

5. A control device comprising switch means, an overcenter member foractuating said switch means, a lever operable to move said memberovercenter, an abutment carried by said lever and extending from oneface thereof, a power element operable to move said lever, a coil springopposing movement of said lever by said element and engageable with saidabutment, a second lever concentrically fulcrum-ed with and movable bysaid first-named lever and having an aperture through which saidabutment extends, a second coil spring positioned adjacent and parallelto said first-named spring and opposing movement of said second lever bysaid first-named lever, means to limit movem nt of said second lever bysale second spring prior to movement of said overcenter memberovercenter in one direction, said second lever being moved by saidfirst-named lever prior to movement of said overcenter member overcenterin another direction, means to adjust the forces of said springs, and aunitary locking means for holding said adjusting means in position.

6. A control device comprising a casing having top and bottom walls anda rear wall, a bracket member secured to said bottom wall, a shaftsupported by said bracket member and extending parallel to said bottomwall and normal to said rear wall, a lever journaled on said shaft, anabutment member extending upward from said lever, a second leverjournaled on said shaft and overlying said first-named lever, saidsecond-named lever having an aperture therethrough through which saidabutment member extends, an adjustable abutment member carried by saidtop wall, a coil spring under compression and positioned between saidabutment members, a stop member secured to said second-named lever andhaving a flange engageable by said firstnamed lever, an adjustablesupporting member carried by said top wall, a coil spring under tensionand secured to said supporting member and to said stop member, aU-shaped locking member secured to said rear wall and engageable withsaid adjustable abutment member and with said supporting member to holdsaid members in adjust-ed position, an upstanding arm on saidfirst-named lever and having a flange normal to said rear wall, aflexible blade secured to and extending upward beyond said flange, anadjustment screw for regulating the position of said blade and carriedby said flange, a switch housing mounted on said rear wall, overcenterswitch means in said housing, a plunger reciprocal through the wall ofsaid housing and operable to actuate said switch means, said plungerextending parallel to said rear wall and having a converging-divertingslot in its rear face receiving said blade, and means to close theaperture in said housing around said plunger.

7. In an apparatus of the character described for controlling acontrolled means, a controlling means having two positions of operationfor controlling the controlled means, power means sensitive to acondition of the controlled means and operable to move said controllinmeans to either of said positions, and a second power means normallydisengaged from said controlling means and sensitive to a secondcondition of the controlled means and operable to move said controllingmeans to either of said positions irrespective of said first-named powermeans, said controlling means having a third position, said first-namedpower means being operable to move said controlling means to said thirdposition upon a predetermined abnormal condition of the controlledmeans.

8. In an apparatus of the character described for controlling acontrolled means, a controlling means having two positions of operationfor controllin the controlled means, power means sensitive to acondition of the controlled means and operable to move said controllingmeans to either of said positions, a second power means normallydisengaged from said controlling means and sensitive to a secondcondition of the controlled means and operable to move said controllingmeans to either of said positions irrespective of said first-named powermeans, said controlling means having a third position, said first-namedpower means being operable to move said controlling means to said thirdposition upon a predetermined abnormal condition of the controlledmeans, and means sensitive to a third condition of the controlled meansand operable to render said first-named power means ineffective.

9. In an apparatus of the character described, a power element, a pairof spring-urged lever members operable to be moved by said powerelement, stop means for limiting rotational movement of said members,means connecting said members and said element so that said element isoperable to move one of said members into engagement with said stopmeans and then to move the other of said members out of engagement withsaid stop means.

10. In an apparatus of the character described, a casing, a pair ofoverlying pivoted levers carried by said casing, one of said levershaving a shoulder, thrust means, means urging said thrust means intoengagement with said shoulder, a stop member interposed intermediatesaid levers to limit rotation thereof, resilient means urging the otherof said levers against said stop member, resilient means urging said onelever away from said stop member, and power means engaging said thrustmeans and operable to rotate said one lever against the force of saidsecond-named resilient means into engagement with said stop member, saidpower means bein operable upon engagement of said one lever and saidstop member to move said other lever against the force of saidfirst-named resilient means out of engagement with said stop member.

11. In an apparatus of the character described, a casing, a pair ofoverlying pivoted levers carried by said casing, one of said levershaving a shoulder, thrust means, means urging said thrust means intoengagement with said shoulder, a stop member interposed intermediatesaid levers to limit rotation thereof, resilient means urging the otherof said levers against said stop member, resilient mean urging said onelever away from said stop member, power means engaging said thrust meansand operable to rotate said one lever against the force of saidsecond-named resilient means into engagement with said stop member, saidpower means being operable upon engagement of said one lever and saidstop member to move said other lever against the force of saidfirst-named resilient means out of engagement with said stop member, andmeans for ad justing the force required by said power means to rotatesaid levers.

12. In an apparatus of the character described, an overcenter meansmovable into two positions of operation, a pressure sensitive element,lever means operatively connecting said element and said means, meansacting on said lever means and operable to oppose movement of saidovercenter means by said element to the first of said positions, saidelement being operable upon a predetermined pressure to overcome saidacting means and to move said overcenter means to said first position,said acting means being operable to move said overcenter means to thesecond of said positions upon a second pressure in said element, asecond pressure sensitive element, means operatively connecting saidsecond element and said overcenter means, said second element actingthrough said connecting means to oppose movement of said overcentermeans to said second position thereby to modulate and vary the secondpressure at which said acting means acts to overcome said first-namedelement to move said overcenter means to said second position.

13. In an apparatus of the character described, an overcenter meansmovable into two positions of operation, a pressure sensitive element,lever means connecting said element and said means, resilient meansacting on said lever means and operable to oppose movement of saidovercenter means by said element to the first of said positions, saidelement being operable upon a predetermined pressure to overcome saidresilient means and to move said overcenter means to said firstposition, said resilient means being operable to move said overcentermeans to the second of said positions upon a second pressure in saidelement, a second pressure sensitive element, lever means connectingsaid second element and said first-named lever means, said secondelement acting through said connecting means to oppose movement of saidovercenter means to said second position thereby to modulate and varythe second pressure at which said resilient means acts to overcome saidfirstnamed element to move said overcenter means to said secondposition.

14. In an apparatus of the character described, a pressure sensitivepower element, an overcenter electric switch means having open andclosed positions, means operatively connecting said switch means andsaid element and having two positions, said element being operable upona predetermined fluid pressure to move said connecting means to one ofsaid positions, said connecting means being operable upon movement tosaid one position to move said switch means to said closed position,means urging said connecting means toward another of said positionsagainst the force of said element, said urging means being operable upona reduction of fluid pressure in said element to move said connectingmeans to said another position, said connecting means being operableupon movement to said another position to move said switch means to saidopen position, and pressure sensitive means cooperable with saidconnecting means and operable to oppose said urging means thereby tomodulate the pressure of said element at which said switch means will bemoved to said open position by said urging means.

15. In an apparatus of the character described, a pair of lever membershaving overlying portions, a power element having an operating partoverlying said portions, resilient means urging one of said members inone direction, resilient means urging the other of said members in saidone direction, stop means limiting movement of said one member in saidone direction and limiting movement of said other member in a directionopposite to said one direction, thrust means engaging said one memberportion and carried by said other member portion and engaged by saidoperating part, resilient means urging said thrust means in a directiontoward said operating part, and stop means limiting movement of saidthrust means by said last-named resilient means.

16. In an apparatus of the character described, a pair of lever membershaving overlying portions, a power element having an operating partoverlying said portions, resilient means urging one of said members inone direction, resilient means urging the other of said members in saidone direction, stop means limiting movement of said one member in saidone direction and limiting movement of said other member in a directionopposite to said one direction, thrust means engaging said one memberportion and carried by said other member portion and engaged by saidoperating part, resilient means urging said thrust means in a directiontoward said operating part, and stop means limiting movement of saidthrust means by said last-named resilient means, said last-namedresilient means exerting a greater force than the maximum force exertedby said second-named resilient means.

17. A control device comprising control means, an overcenter member foractuating said control means, a lever member for moving said overcentermember, a power element operable to move said lever member, meansopposing movement of said lever by said element, a second lever, meansopposing movement of said second lever, said first-named lever beingoperable to move said second lever against the force of said lastnamedopposing means prior to movement of said overcenter member overcenter inone direction, and stop means limiting movement of said second lever bysaid last-named opposing means prior to movement of said overcentermeans overcenter in a second direction.

18. In an apparatus of the character described, a casing having a wallwith an aperture therethrough, a pair of overlying leaf springs carriedby said casing, each of said springs having two bowed positions withinsaid casing, a pair of overlying flexible blade members, one of saidblade members having one end rigidly secured to said casing and havingits other end operatively carried by one of said springs, the other ofsaid blade members having one end rigidly secured to said casingadjacent said one blade member and having its other end operativelycarried by the other of said springs, a pair of contact members carriedby said casing, a contact member secured to and carried by each of saidblade members and cooperable with said first-named contact members tocontrol a pair of electric circuits, a plunger member carried by saidcasing in said aperture, said plunger member being operable uponmovement to move each of said springs to each of their said twopositions, lost motion means connecting said plunger member to each ofsaid blade members, said lost motion means having greater lost motionrelative to one of said blade members than it has relative to the otherof said blade members so that said plunger member will move the blademember connected with the smaller lost motion prior to movement of theblade member connected with the greater lost motion.

19. In an apparatus of the charac er described, a casing, a flexibleblade secured at one end to said casing and having its other end portiontwisted into the plane of movement of said blade, said other end portionhaving an end slot, a leaf spring carried by said casing and having abowed position, said spring having its edge portion extending into saidslot and lying substantially in the plane of said blade, control meanscarried by said blade, and an operating member extending transverse tosaid spring, said operating member having a plate-like portion with anedge slot receiving said spring such that said operating member can movesaid spring from said bowed position.

20. In an apparatus of the character described, a wall member having anaperture therethrough, a U-shaped member carried by said wall member andhaving a pair of opposed slots, a bowed leaf spring carried by saidU-shaped member with its end portions within said slots, said springbeing positioned adjacent said aperture and having two positions ofrest, a plunger member slidable within said aperture and operable tomove said bowed spring to each of said positions, said plunger memberhaving a hook portion, said bowed spring being carried in said hookportion, a blade member extending substantially normal to the plane ofmovement of said bowed spring and extending substantially parallel tosaid wall member, said blade member having one end portion carried bysaid wall member and having its other end portion operatively connectedto said bowed spring, and a control means movable by said blade memberupon movement of said bowed spring over center.

21. In an apparatus of the character described, a supporting member, alever member fulcrumed on said member, a power element secured to saidsupporting member and operable to move said lever member, an opposingmeans operable to oppose movement of said lever member by said powerelement, a switch means carried by said supporting member and having areciprocal thrust member movable between predetermined limits, and asemi-rigid blade member movable by said lever member and operable uponmovement to move said thrust member, said blade member having a rigiditysuch that substantially no flexing occurs prior to movement of saidthrust member to one of said predetermined limits and having suchflexibility that subsequent to movement of said thrust member to saidone predetermined limit said blade member will flex thereby to allowcontinued movement of said lever member.

22. In an apparatus of the character described, a supporting member, alever member fulcrumed on said member, an arm member carried by andextending outwardly from said lever member, a power element secured tosaid supporting member and operable to move said lever member, anopposing means operable to oppose movement of said lever member by saidpower element,

a switch means carried by said supporting member, a semi-rigid blademember carried by said arm member and having its free end urged towardsaid arm member due to the innate resiliency of said blade member, saidblade member being movable with said lever member and operable uponmovement to operate said switch means, said blade member having arigidity such that substantially no flexing occurs upon operation ofsaid switch means by said lever member, and means carried by said armmember and engaging said blade member for flexing said blade memberagainst its innate resiliency and away from said arm member thereby toadjust the position at which said lever member actuates said switchmeans.

23. In a control device, a housing, a shaft in said housing, a bellcrank lever supported by said shaft, a power element carried by saidhousing and acting on one arm of said lever, a spring in said housingand opposing movement of said lever by said power element, the other armof said lever extending longitudinally of said spring, an operatingblade secured at one end to said other arm and extending therebeyond, anabutment member on said other arm holding said blade under stress anddetermining the position of said blade relative to said other arm, acontrol means, and a plunger extending transverse to said blade andoperatively connecting the extending portion of said blade to saidcontrol means.

24. In a control device, a housing, a shaft in said housing, a bellcrank lever supported by said shaft, a power element carried by saidhousing and acting on one arm of said lever, a. spring in said housingand opposing movement 01 said lever by said power element, the other armof said lever extending longitudinally of said spring, an operatingblade secured at one end to said other arm and extending therebeyond, anabutment member on said other arm holding said blade under stress anddetermining the position of said blade relative to said other arm, acontrol means, a plunger having a slot receiving the extending portionof said blade, and means operatively connecting said plunger to saidcontrol means.

25. A control device comprising a casing having top and bottom walls anda rear wall, a bracket member secured to said bottom wall, a shaftsupported by said bracket member and extending parallel to said bottomwall and normal to said rear wall, a lever journaled on said shaft, anabutment member extending upward from said lever, a second leverjournaled on said shaft and overlying said first-named lever, saidsecondnamed lever having an aperture therethrough through which saidabutment member extends, an adjustable abutment member carried by saidtop wall, a coil spring under compression and positioned between saidabutment members, a stop member secured to said second-named lever andhaving a portion engageable by said first-named lever, an adjustablesupporting member carried by said top wall, a coil spring under stressand cooperable with said supporting member and with said second lever, aU-shaped looking member secured to said rear wall and engageable withsaid adjustable abutment member and with said supporting member to holdsaid members in adjusted position, an upstanding arm on said first-namedlever and having a flange normal to said rear wall, a flexible bladesecured to and extending upward beyond said flange,

means for positioning said blade relative to said flange, a switchhousing mounted on said rear wall, overcenter switch means in saidhousing, a plunger reciprocal through the wall of said housing andoperable to actuate said switch means, said plunger extending parallelto said rear wall and having an aperture receiving said blade, and meansto close the aperture in said housing around said plunger.

26. A control device comprising a casing having top and bottom walls anda rear wall, a bracket member secured to said bottom Wall, a shaftsupported by said bracket member and extending parallel to said bottomwall and nor mal to said rear wall, a lever journaled on said shaft, anabutment member extending upward from said lever, a second leverjournaled on said shaft and overlying said first-named lever, saidsecond-named lever having an aperture therethrough through which saidabutment member extends, an adjustable abutment member carried by saidtop wall, coil spring under compression and positioned between saidabutment members, a stop member secured to said second-named lever andhaving a portion engageable by said firstnamed lever, an adjustablesupporting member carried by said top wall, a coil spring under stressand cooperable with said supporting member and with said second lever,an upstanding arm on said first-named lever and having a flange normalto said rear wall, a flexible blade secured to and extending upwardbeyond said flange, means for positioning said blade relative to saidflange, a switch housing mounted on said rear wall, overcenter switchmeans in said housing, and a, plunger reciprocal through the wall or"said housing and operable to actuate said switch means, said plungerextending parallel to said rear wall and having an aperture receivingsaid blade.

27. A power element comprising a housing member, a pressure sensitivechamber carried by said member and having a movable wall, means understress and operatively opposing movement of said wall in one direction,a first lever member fulcrumed on said housing member and positioningone portion of said stressed means against movement in said onedirection, means positioning said lever member against movement in saidone direction, a second lever member fulcrumed on said housing member, athrust means operativel connecting said wall and said second levermember and operable upon movement of said wall in said one direction torotate said second lever member, and means operatively connected to saidsecond lever member and operated upon rotation of said second levermember.

28. A power element comprising a housing member, a pressure sensitivechamber carried by said member and having a movable wall, means understress and operatively opposing movement of said wall in one direction,a first lever member fulcrumed on said housing member and positloningone portion of said stressed means against movement in said onedirection, means positioning said lever member against movement in saidone direction, a second lever member fulcrumed on said housing memberand having a portion underlying said first lever member, said firstlever member having an aperture therethrough overlying said second levermember, thrust means operatively connecting said wall and said secondlever member and extending through said aperture, said thrust meansbeing operable upon movement of said wall in said one direction torotate said second lever member, means under stress intermediate saidhousing member and said second lever member and being operable to opposerotation of said second lever member by said thrust means, and meansengageable by said second lever member and operable to be moved by andupon rotation of said second lever member,

29. A control device comprising a U-shaped casing with open end portionsand having topand bottom walls and having a connecting rear wall, a postmember connecting said top wall and said bottom wall adjacent the edgeportion away from said rear wall and coacting with said rear wall tohold said top wall and said bottom wall in fixed space relation, abracket member having spaced upturned flanges and secured to the topsurface of said bottom wall, a shaft having its end portions secured inaligned apertures extending through said flanges and extendingsubstantially parallel to said bottom wall and extending substantiallynormal to said rear wall, a platelike lever member having substantiallyperpendicularl extending flange portions, said lever member flangeportions having aligned apertures for receiving said shaft thereby toposition said lever member for rotational movement, said bottom wallhaving an aperture therethrough underlying said lever member, a pressuresensitive power element having a thrust member and positioned againstthe lower surface of said bottom wall, said thrust member extendingthrough said bottom wall aperture and being operable to engage and beingoperable to move said lever member upon change in pressure within saidelement, one of said lever member flanges having an upwardly extendingportion providing a blade carrying portion, a semi-rigid blade memberhaving one end portion thereof rigidly secured to said blade carryingportion and having its other end portion extending upwardly toward saidtop wall and extending beyond said blade carrying portion, a switchstructure operable to control an electric circuit and secured to theinher surface of said rear wall between said top and bottom walls andhaving a reciprocal actuating member extending substantially parallel tosaid casing walls, means operatively connecting said blade member atsaid blade member other end portion for actuation of said switch uponsaid rotational movement of said lever member, said blade member havingsufficient rigidity to reciprocate said reciprocal actuating member withsubstantially no flexing but having suflicient flexibilit to bend uponthe application of a force greater than that required to reciprocatesaid reciprocal actuating member, means carried by said casing andengageable with said blade other end portion for flexing said blademember thereby to actuate said switch irrespective of the position ofsaid lever member, a, U-shaped cover member cooperable with said casingmember to form an enclosed space containing said lever member and saidswitch, and a holding means securing said cover member to said postmember.

30. A control device comprising a U-shaped casing with open end portionsand having top and bottom walls and having a connecting rear wall, apost member connecting said top wall and said bottom wall adjacent theedge portion away from said rear wall and coacting with said rear wallto hold said top wall and said bottom wall in fixed space relation, abracket member having spaced upturned flanges and secured to the topsurface of said bottom wall, a shaft having its end portions secured inaligned apertures extending through said flanges and extendingsubstantially parallel to said bottom wall and extending substantiallynormal to said rear wall, a plate-like lever member having substantiallyperpendicularly extending flange portions, said lever member flangeportions having aligned apertures for receiving said shaft thereby toposition said lever member for rotational movement, said bottom wallhaving an aperture therethrough underlying said lever member, a pressuresensitive power element having a thrust member and positioned againstthe lower surface of said bottom wall, said thrust member extendingthrough said bottom wall aperture and being operable to engage and beingoperable to move said lever member upon change in pressure within saidelement, one of said lever member flanges having an upwardly extendingportion providing a blade carrying portion, a semi-rigid blade memberhaving one end portion thereof rigidly secured to said blade carryingportion and having its other end portion extending upwardly toward saidtop wall and beyond said blade carrying portion, a switch structureoperable to control an electric circuit and secured to the inner surfaceof said rear wall between said top and bottom walls and having areciprocal actuating member extending substantially parallel to saidcasing walls, means for positioning said blade member other end portionrelative to said blade carrying portion thereby to determine theposition of said lever member at which said circuit is controlled, meansoperatively connecting said blade member at said blade member other endportion for actuation of said switch upon said rotational movement ofsaid lever member, said blade member having suflicient rigidity toreciprocate said reciprocal actuating member with substantially noflexing but having suflicient flexibility to bend upon the applicationof a force greater than that required to reciprocate said reciprocalactuating member, means carried by said casing and engageable with saidblade other end portion for flexing said blade member thereby to actuatesaid switch irrespective of the position of said lever member, aU-shaped cover member cooperable with said casing member to form anenclosed space containing said lever member and said switch, and a thumbscrew extending through an aperture in said cover member andscrew-threadedly engaging said post member for securing said covermember to said casing.

31. In an apparatus of the character described for controlling acontrolled means, a controlling means having two positions of operationfor controlling the controlled means, power means sensitive toacondition of the controlled means and operable to move said controllingmeans to either ofv said positions, flexible means operable to transmita force from and connecting said power means to said controlling meansand having sumcient rigidity so that bodily movement thereof by saidpower means correspondingly transmits the movement of said power meansto said controlling means, a second power means sensitive to a secondcondition of the controlled means, and means operable by said secondpower means and for transmitting a force through said flexible means tomove said controlling means to either of said positions, said last-namedmeans being operable to flex said flexible means in two directionsagainst the force of said first-named power means thereby to move saidcontrolling means irrespective of the force exerted by said firstnamedpower means.

32. In an apparatus of the character described for controlling acontrolled means, a controlling means having two positions of operationfor controlling the controlled means, a first power means sensitive to acondition of the controlled means, force transmitting means movable bysaid power means, means carried by said transmitting means andinterconnecting said transmitting means and said controlling means andnormally operable upon bodily movement thereof by said transmittingmeans to move said controlling means to either of said controlling meanspositions and substantially in direct accordance with movement of saidpower means, a second power means sensitive to a second condition of thecontrolled means, and lost motion means operatively connecting saidsecond power means to said interconnecting means for movement thereofrelative to said transmitting means in either direction upon actuationby said second power means, said second power means acting through saidconnecting means to transmit its force through said interconnectingmeans thereby to move said controlling means to either of saidcontrolling means positions irrespective of the position of said firstpower means.

EARNEST J. DILLMAN.

Patent No. 2,292,2ih.

CERTIFICATE OF CORRECTION.

August 1;, 19L 2.

EARNEST J. DILIMAN.

It is hereby certified that error appears in the printed specificationof the above nuin bered patent requiring correction as follows: Page 7second column, line 55, claim 2, strike out "concentrically fulcrumedwith and"; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office. 7

Signed and sealed this 15th day of October, A. D. l9LL2. I

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

Patent No. 2,292,211.

CERTIFICATE OF CORRECTION.

' August 1;, 19l|.2.

EARNEST J. DILLMAN.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows Page 7 sec-0nd column, line 55, claim 2, strike out "concentrically fulcrumed withand"; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 15th day of October, A. D. 1914.2. I

Henry Van Arsdale,

(Seal) 1 Acting Commissioner of Patents.

